Evidence for “Pseudo-Liquid Phase” in the Dehydration of Isopropanol Over H3pw12o40

Okuhara, Toshio; Hashimoto, Tomihito; Misono, Makoto; Yoneda, Yukio; Niiyama, Hiroo; Saito, Yoshinori; Echigoya, Etsuro

doi:10.1246/cl.1983.573

Cited by 37 publications

(11 citation statements)

References 4 publications

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“…This type of catalysis has not been found for usual acidcatalyzed reactions. [17,18], because these reactions proceed through the bulk-type I (pseudo-liquid) catalysis and the entire protons (on the surface and in the bulk) can take part in acid-catalysis. Hence, the surface area is a minor factor.…”

Section: Basic Concepts Of Solid Hpa Catalystsmentioning

confidence: 99%

Catalytic Chemistry of Supported Heteropolyacids and Their Applications as Solid Acids to Industrial Processes

et al. 2008

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This article reviews recent research and development of supported heteropolyacid (HPA) catalysts; focusing on the acidic and catalytic properties. First the basic knowledge of solid HPAs is provided briefly to facilitate understanding of heterogeneous catalysis of HPAs. Secondly, the structure as well as the physical and chemical properties of supported HPA catalysts is described. Especially the layer structure of HPA dispersed on the surface of SiO 2 and the changes in the surface acidity with the loading level of HPA are discussed. For this purpose, temperature programmed desorption of benzonitrile devised by Okuhara and Kamiya's group is useful. This method is capable to assess the surface acidity of the supported HPA, which controls the catalytic activity for the reactions proceeding by surface-type catalysis. Then, two new industrial processes developed by Showa Denko K. K. are described; (i) production of ethyl acetate from ethylene and acetic acid and (ii) oxidation of ethylene to acetic acid. Supported HPA catalysts are utilized for both processes, which were recently much improved by finely controlling the catalysts and reaction conditions.

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Section: Basic Concepts Of Solid Hpa Catalystsmentioning

confidence: 99%

Catalytic Chemistry of Supported Heteropolyacids and Their Applications as Solid Acids to Industrial Processes

et al. 2008

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“…As to bulk PTA, a BPF yield of about 46% was obtained, higher than that of Pa and H-Beta zeolite because it can act as a pseudo liquid phase catalyst due to partial solubility in the reaction medium. 20 Generally, the catalytic activities of the catalysts are low with the lowest/highest B/L ratio. PTA/Pa composites with a tunable surface acidity (or an appropriate B/L ratio) prepared by impregnating different mass ratios of PTA are more active as compared with bulk PTA, Pa or H-Beta zeolite.…”

Section: Catalyst Activitymentioning

confidence: 99%

Green synthesis of bisphenol F over 12-phosphotungstic acid supported on acid-activated palygorskite

et al. 2015

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“…[2]. Heteropoly compounds resemble liquids in the way they absorb such large amounts of gaseous species [18]. This ability of heteropoly substrates to absorb molecules into the bulk allows reactions to proceed with surface area-independent kinetics, that is, surface area does not impact on the reaction rates [17].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Study of Isobutane Selective Oxidation Over Group I and II Phosphomolybdates: Structural and Kinetic Factors

Kendel

Brown

2011

Catal Lett

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Various phosphomolybdates were synthesized using cations from Groups 1 and 2 of the periodic table. These compounds were of the form M x H 3-xn [PMo 12 O 40 ], with n being the cationic charge (?1 or ?2). XRD analysis shows pure phosphomolybdic acid has a triclinic structure. A body centered cubic (BCC) structure gradually develops with addition of Group 1 cations, and the triclinic phase is completely replaced by the BCC phase once metal cations occupy a volume greater than 9-11 Å 3 per phosphomolybdate anion. The Group 2 compounds do not form a cubic phase, however the triclinic phase distorts once cationic volume is greater about 5 or 6 Å 3 and appears to become somewhat amorphous. Isobutane selective oxidation over the compounds yielded methacrolein (primary product), 3-methyl-2-oxetanone (lactone), acetic acid, propene, methacrylic acid, carbon dioxide and water as products. Propene was formed over the Group 1 compounds exclusively and methacrylic acid formation was observed with BaH[PMo 12 O 40 ] only. Products form via two distinct processes: Category 1 product has an exponential profile and coverage is consistent with a Langmuir model, Category 2 formations are consistent with desorptions from within the bulk of the substrates. Methacrolein forms via both Category 1 and 2 processes, whilst all other products are formed by Category 2 exclusively. A rigorous kinetic analysis yielded accurate activation parameters. Category 1 methacrolein formation apparent activation energies ranged from 34.7 ± 1.3 to 119 ± 4 kJ mol -1 . Category 2 formations ranged from 34.3 ± 0.4 to 726 ± 172 kJ mol -1 . No relationship between activity and composition or structure could be ascertained, despite investigation into correlations using several different models.

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Evidence for “Pseudo-Liquid Phase” in the Dehydration of Isopropanol Over H3pw12o40

Cited by 37 publications

References 4 publications

Catalytic Chemistry of Supported Heteropolyacids and Their Applications as Solid Acids to Industrial Processes

Catalytic Chemistry of Supported Heteropolyacids and Their Applications as Solid Acids to Industrial Processes

Green synthesis of bisphenol F over 12-phosphotungstic acid supported on acid-activated palygorskite

Comprehensive Study of Isobutane Selective Oxidation Over Group I and II Phosphomolybdates: Structural and Kinetic Factors

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